CeO2 / ZrO2 (at) p-beta-CD nano-enzyme and application of CeO2 / ZrO2 (at) p-beta-CD nano-enzyme in catalytic visual detection of cartap

Abstract

The invention particularly relates to a CeO2 / ZrO2 (at) p-beta-CD nano-enzyme and application of the CeO2 / ZrO2 (at) p-beta-CD nano-enzyme in catalytic detection of cartap. The CeO2 / ZrO2 (at) p-beta-CD provided by the invention has excellent synergistic enhancement simulation oxidase activity, and can quickly catalyze and oxidize 3, 3 ', 5, 5'-tetramethyl benzidine (TMB), so that colorless TMB is converted into blue oxide (oxTMB). Due to the existence of a trace amount of agricultural residual cartap, the mimic enzyme catalytic activity of CeO2 / ZrO2 (at) p-beta-CD can be obviously changed, so that blue oxTMB is converted into colorless TMB, and an obvious color reduction effect is shown. Under optimized conditions, the method is successfully applied to detection of cartap in environmental water, tea leaves and crops, and is applied to tracking of the time and process of sufficient degradation of cartap by plants under natural conditions, the detection limit is 3.76 * 10 < 8 > g / mL, and the relative error is lower than 3.53%. The method has the advantages of convenience, rapidness, high selectivity, high sensitivity, high interference resistance, strong visibility and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of oxide mimic enzymes, in particular to a CeO2 / ZrO2@ p-β -CD nanozyme, a preparation method of the nanozyme and its application as an oxide mimetic enzyme in catalytic detection of cartap. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Pesticides play a pivotal role in agricultural production, but the problem of pesticide residues is an important issue for people's food safety. Pesticide residues may be enriched in the human body through the food chain, causing serious physiological diseases, such as acute poisoning, vomiting, and breathing difficulties. Some pesticides may even damage the human nervous system, leading to severe convulsions, respiratory failure and other symptoms. Among them, cartap is an insecticide related to haron toxin, which is derived from haron toxin isolated from marine annelid worms. It directly inhibits the central nervous system of insects and has a wide range of activity against various insects. It is the best choice for controlling chewing and sucking insects. Due to its low toxicity and high insecticidal activity, cartap has been widely used in the agricultural field to control various pests of rice, vegetables, tea trees, fruit trees and other crops. Due to the biomagnification effect of the food chain, cartap will be enriched in the human body and cause physiological diseases. Among them, the European Commission limits the content of cartap in tea to 0.1 mg / kg, while China sets the maximum limits of cartap in tea and sugarcane to 20 mg / kg and 0.1 mg / kg, respectively. At present, several analytical methods for the determination of cartap have been established, such as high performance liquid chromatography, gas chromatography (GC), GC-mass spectrometry, and polarography. However, most of these methods either require expensive instruments and complex operations, or have low sensitivity and poor selectivity. Therefore, there is an urgent need to develop a sensor that can be fast, accurate, convenient, highly sensitive, and has a strong anti-interference effect to detect pesticide residues cartap in food and environmental samples. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention aims to provide a Ce-Zr alloy oxide modified polycyclodextrin preparation and its application in catalytic visual detection of pesticide residue carbofuran. 4+ and Ce 3+ After mixing, stir for 2 h to ensure that Zr 4+ and Ce 3+CeO2 / ZrO2@ was prepared by microwave-assisted hydrothermal method after being fully bonded with polycyclodextrin through strong electrostatic interaction. p-β The material can not only improve the catalytic activity of the oxidative mimetic enzyme and the visibility and sensitivity of the catalytic detection of cartap, but also further expand the practical application of the catalytic performance of the nanozyme and the amplification of the visual signal of the enzyme catalysis, and realize the naked eye detection of cartap.

[0005] Based on the above technical effects achieved by the present invention, the present invention provides the following technical solutions: In a first aspect, the present invention provides a CeO2 / ZrO2@ p-β -CD nanozyme, the nanozyme uses polycyclodextrin as a carrier and loads CeO2 and ZrO2 crystals through chelation. Through electron microscopy observation, the above nanozyme presents a three-dimensional porous network structure.

[0006] The mass ratio of CeO2 and ZrO2 crystals to polycyclodextrin in the above material is 1.55:0.105:1. CeO2 and ZrO2 have the activity of simulating superoxide dismutase, and can degrade active oxygen substances into harmless chemical substances. In the above simulated enzyme, CeO2 and ZrO2 are in the form of crystals with higher purity; polycyclodextrin as a carrier presents a three-dimensional porous network structure, which provides abundant attachment sites for loading CeO2 and ZrO2 crystals, and the present invention adopts a simple "one-pot synthesis method" for synthesis, and the preparation process is simple.

[0007] In a second aspect of the present invention, there is provided the CeO2 / ZrO2@ p-β -CD nanozyme preparation method, Ce(NO3)3·6H2O, ZrCl4, ethylene glycol are added to the aqueous solution of polymerized cyclodextrin to make them dispersed evenly; after adding ammonia water, the above nanozyme is prepared by microwave-assisted hydrothermal synthesis.

[0008] The above preparation method also has the following preferred embodiment: The aqueous solution of the above polymerized cyclodextrin is prepared as follows: 4.5-5.5 mg of water-soluble polymerized cyclodextrin is added to 4.0-5.0 mL of water, and the water is fully dissolved by stirring or ultrasonication.

[0009] The concentration of the ammonia water is 25-28%. After adding the ammonia water, the reaction system should be fully stirred to make it uniformly mixed. The feasible stirring time is, for example, 1.5-2.5 h.

[0010] The dosage ratio of the above Ce(NO3)3·6H2O, ZrCl4, ethylene glycol, aqueous solution of polymerized cyclodextrin and aqueous ammonia is 17~22 mg: 1.0~1.30 mg: 20 mL: 4.0~5.0 mL: 750~850 μL.

[0011] The reaction parameters of the microwave-assisted hydrothermal synthesis are as follows: 105-115°C, 12-20 min, 650-750 W. The reaction product after microwave-assisted hydrothermal synthesis is centrifuged to retain the solid part, and the nanozyme is obtained after washing.

[0012] The present invention provides the nanozyme that can catalyze the conversion of common chromogenic substrates such as 3,3',5,5'-tetramethylbenzidine hydrochloride dihydrate (TMB) and can be used as an oxide mimetic enzyme. Therefore, the third aspect of the present invention provides the use of the nanozyme described in the first aspect as an oxide mimetic enzyme.

[0013] In addition, the present invention verifies that p-β -CD@CeO2-ZrO2-TMB system has a special color reduction response to cartap, and has good sensitivity and specificity when applied to the detection of cartap content in liquid environment. Therefore: According to a fourth aspect of the present invention, a catalytic sensor of cartap is provided, wherein the sensor comprises the nanozyme described in the first aspect and a chromogenic substrate.

[0014] The above-mentioned chromogenic substrate includes but is not limited to o-phenylenediamine (OPD), 3,3',5,5'-tetramethylbenzidine (TMB), etc. In one embodiment verified by the present invention, the chromogenic substrate is TMB. In this embodiment, the preparation method of the above-mentioned catalytic sensor is as follows: the nanozyme, TMB (1.3~1.6 mM) and citric acid-disodium hydrogen phosphate buffer solution (pH3.5~4.5) described in the first aspect are mixed and aged at room temperature, with a dosage ratio of 0.45~0.55 mg: 120~170 μL: 6~10 mL. After mixing evenly, age at room temperature for 35~45 min.

[0015] In a fifth aspect, the present invention provides a catalytic detection method for cartap, comprising the following steps: preparing the catalytic sensor described in the fourth aspect, adding 50-70 μL of the sample to be tested to the sensor reaction system, mixing evenly at room temperature and aging for 4-6 min, detecting the absorbance value by ultraviolet spectroscopy, and calculating the absorbance value by linear equation ∆ A 652 =2.281×10 −4 c cartap −0.0041Calculate the concentration of cartap in the test sample.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes a preparation method of Ce-Zr alloy oxide modified polycyclodextrin and its application in catalytic visual detection of pesticide residue carbofuran. Polycyclodextrin and Zr alloy oxide modified polycyclodextrin are firstly reacted with each other through a simple "one-pot synthesis method". 4+ and Ce 3+ After mixing, stir for 2 h to ensure that Zr 4+ and Ce 3+ CeO2 / ZrO2@p-β-CD was prepared by microwave-assisted hydrothermal method after being fully bonded with polycyclodextrin through strong electrostatic interaction. The nanozyme has the advantages of high stability, good enzyme-like catalytic performance, high sensitivity, high selectivity, good reproducibility, and convenient detection. In the process of visual detection of cartap, an obvious color reduction effect is presented. As the concentration of cartap increases, the color of the CeO2 / ZrO2@p-β-CD-TMB system changes from blue to colorless, which realizes the signal amplification of cartap detection, enhances visibility, and realizes the naked eye detection of cartap. At the same time, the method is simple to operate, highly sensitive, non-toxic and pollution-free, and can be effectively applied to the detection of cartap in agricultural products.

[0017] Secondly, the present invention also explores CeO2 / ZrO2@ p-β -CD-TMB system, the pH value, TMB dosage, reaction time, and the interference of coexisting substances were taken into consideration to determine the optimal enzyme performance conditions. Under the optimal enzyme performance conditions, the influence of other common interfering substances was eliminated, and a quantitative analysis titration experiment of cartap was conducted to obtain its UV spectrum titration curve and draw a linear regression equation. When the concentration of cartap was 8.00×10 −8 ~2.00×10 −5 g / mL, ΔA 652 =2.281×10 − 4 c Cartap −0.0041(10 −8 g / mL), the correlation coefficient (R) was 0.9987, and the detection limit was 3.76×10 −8 g / mL. According to the linear regression equation, it was successfully applied to the detection of cartap content in common agricultural products, with a recovery rate of 97.4%~103.4% and an RSD of less than 3.06%. It has good detection performance for the residual detection of cartap in liquid environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0019] Figure 1 CeO2 / ZrO2@ prepared under different conditions p-β -UV spectrum test results of CD nanozyme at 652 nm; in, Figure 1 a is the mass concentration of polycyclodextrin; Figure 1 b is the molar feed ratio of Ce to Zr; Figure 1 c is the amount of ammonia water used; Figure 1 d is the reaction temperature; Figure 1 e is the reaction time; Figure 2 The CeO2 / ZrO2@ p-β -SEM structural characterization of CD nanozyme; Figure 3 The structural characterization of CeO2 / ZrO2@p-β-CD nanozyme described in Example 1; in, Figure 3 a is the XRD pattern; Figure 3 b is FT-IR image; Figure 3 c is the zeta potential diagram; Figure 4 The CeO2 / ZrO2@ p-β -The effect of CD nanozymes on catalytic oxidation of TMB under different experimental conditions; in: Figure 4 a is the reaction time; Figure 4 b is pH value; Figure 4 c is the dosage of TMB; Figure 5 The CeO2 / ZrO2@ p-β - Results of the exploration of kinetic parameters of CD nanozymes; in, Figure 5 a is CeO2 / ZrO2@ p-β -CD nanozymes and pure CeO2 / ZrO2 nanoparticles c TMB ; Figure 5 b is the double reciprocal curve of 5a, that is, 1 / v-1 / c TMB curve; Figure 6 This is the time scan at 652 nm after adding cartap standard solution under the optimal enzyme performance conditions; Figure 7 As described in Example 4, common ion interferences have an effect on CeO2 / ZrO2@ p-β -CD-TMB system catalyzes visual detection of the effects of cartap; Figure 7 a is p-β -UV-visible spectrum of CD@CeO2-ZrO2-TMB system at 300~800 nm; Figure 7 b shows the effect of common ions and cartap on CeO2 / ZrO2@ p-β -The influence of the absorption intensity of the CD-TMB system at 652 nm; Figure 7 c is the interfering substance to CeO2 / ZrO2@ p-β -Color change impact diagram of CD-TMB system; Figure 7 d is the UV-vis spectroscopic titration curve of catalytic visual detection of cartap; Figure 7 e is ∆ A 652 and c cartap The linear relationship curve of Figure 7 f is the color change corresponding to the ultraviolet spectrum. DETAILED DESCRIPTION

[0020] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0021] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0022] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0023] Example 1 A Ce-Zr alloy oxide modified polycyclodextrin nanozyme (CeO2 / ZrO2@ p-β -CD) and its preparation method: weigh 5.0 mg of water-soluble polymerized cyclodextrin ( p-β-CD) was added to a 100 mL three-necked flask, 4.2 mL of water was added, dissolved under ultrasound, 20 mL of ethylene glycol was added, 19.54 mg (0.045 mmol) of Ce(NO3)3·6H2O and 1.16 mg (0.005 mmol) of ZrCl4 were added, and stirred for 2 h. 800 μL of 25-28% ammonia solution was added, stirred for 2 h, and then microwave-assisted hydrothermal synthesis (110 o C, 15 min, 700 W). After the reaction was completed, it was cooled to room temperature and washed with triple distilled water and centrifuged three times at (6000 r / min, 5 min) to obtain the product CeO2 / ZrO2@ p-β -CD nanozymes.

[0024] Example 2 A Ce-Zr alloy oxide modified polycyclodextrin nanozyme (CeO2 / ZrO2@ p-β -CD) and its preparation method: weigh 4.50 mg of water-soluble polymerized cyclodextrin ( p-β -CD) was added to a 100 mL three-necked flask, 4.0 mL of water was added, dissolved under ultrasound, 20 mL of ethylene glycol was added, 17.00 mg of Ce(NO3)3·6H2O and 1.00 mg of ZrCl4 were added, and stirred for 1.5 h. 750 μL of 25-28% ammonia solution was added, stirred for 1.5 h, and then microwave-assisted hydrothermal synthesis (105 o C, 12 min, 650 W). After the reaction was completed, it was cooled to room temperature and washed with triple distilled water and centrifuged three times at (6000 r / min, 5 min) to obtain the product CeO2 / ZrO2@ p-β -CD nanozymes.

[0025] Example 3 A Ce-Zr alloy oxide modified polycyclodextrin nanozyme (CeO2 / ZrO2@ p-β -CD) and its preparation method: weigh 5.50 mg of water-soluble polymerized cyclodextrin ( p-β -CD) was added to a 100 mL three-necked flask, 5.0 mL of water was added, dissolved under ultrasound, 20 mL of ethylene glycol was added, 22.00 mg of Ce(NO3)3·6H2O and 1.30 mg of ZrCl4 were added, and stirred for 2.5 h. 850 μL of 25-28% ammonia solution was added, stirred for 2.5 h, and then microwave-assisted hydrothermal synthesis (115 oC, 20 min, 750 W). After the reaction was completed, it was cooled to room temperature and washed with triple distilled water and centrifuged three times at (6000 r / min, 5 min) to obtain the product CeO2 / ZrO2@ p-β -CD nanozymes.

[0026] Structural characterization CeO2 / ZrO2@ in Example 1 p-β -CD, whose structure is characterized as follows: ① The CeO2 / ZrO2@ prepared in Example 1 p-β -CD nanozymes were characterized by SEM, XRD, FTIR and ζ potential. p-β -CD nanomaterials structure, such as Figure 2 and 3 shown. Figure 2 SEM confirmed that CeO2 / ZrO2@ p-β -The morphology of CD material is a three-dimensional porous network structure. Figure 3 a is CeO2 / ZrO2@ p-β -CD XRD diffraction pattern, as shown in the figure, has diffraction peaks at 27.81°, 28.64°, 47.35°, and 56.71°, of which the peak at 2θ=27.81° is attributed to the (−111) crystal plane of ZrO2, while the peaks at 2θ=28.64°, 47.35°, and 56.71° are attributed to the (111), (220), and (311) crystal planes of CeO2. This shows that the target CeO2 / ZrO2@ p-β -CD nanozymes have been successfully constructed and have excellent crystallinity.

[0027] In order to illustrate the strong interaction between polycyclodextrin and CeO2 / ZrO2 nanomaterials, this example records the CeO2 / ZrO2@ p-β -CD with p-β - FT-IR spectrum and zeta potential of CD. Figure 3 b p-β -CD and CeO2 / ZrO2@ p-β -CD FT-IR showed that the free polycyclodextrin had the following peaks at 3403, 1643, 1159 and 1033 cm −1 Some characteristic peaks appeared at the CeO2 / ZrO2@ p-β In the FT-IR spectrum of -CD, the above characteristic peaks all appear and are centered at 3432, 1630, 1077, and 1049 cm −1 , with a total displacement of 29, −13, −82, and 16 cm−1 This is due to the CeO2 / ZrO2 nanomaterials and p-β There is a strong chelation between the electron-rich oxygen atoms in the OH, C=O, and CO bonds in -CD.

[0028] For CeO2 / ZrO2@ p-β -CD material related components in aqueous solution, the zeta potential of CeO2 / ZrO2 nanomaterials alone is 17.24 mV, while the CeO2 / ZrO2@ p-β The zeta potential of the CD material is 37.52 mV. Figure 3 c. Its absolute value is significantly higher than that of CeO2 / ZrO2 nanomaterials alone, indicating that there is sufficient electrostatic repulsion to alleviate the CeO2 / ZrO2@ p-β Compared with pure CeO2 / ZrO2 nanomaterials synthesized under similar conditions, the strong interaction between polycyclodextrin and CeO2 / ZrO2 nanomaterials makes CeO2 / ZrO2@ p-β -CD has better stability.

[0029] Example 4 In this embodiment, CeO2 / ZrO2@ p-β -CD and its application in catalytic visual detection of cartap pesticide residues in environmental samples are described. The CeO2 / ZrO2@ prepared in Example 1 p-β -CD nanozyme as an example, perform the following operations: (1) Prepared CeO2 / ZrO2@ p-β -CD material was ultrasonically dispersed into 8 mL of double distilled water and diluted 10 times to obtain a concentration of 0.08 mg / mL CeO2 / ZrO2@ p-β -CD standard solution, stored at room temperature for future use; (2) Prepare 1.0 mL of 1 mg / mL cartap and 10 mL of 1.5 mM TMB standard solutions respectively; (3) Preparation of environmental food samples: 100.0 mL of water samples from the Yihe River and Liaohe River were randomly measured and filtered three times using a microporous filter membrane with a pore size of 0.22 μm and stored at room temperature for later use.

[0030] Randomly pick lettuce, cabbage, Chinese cabbage, cucumber, rice, and black tea from a store near Qufu Normal University, take 5 grams of edible parts, soak them in 100 mL H2O, and put them into a commercial juicer. After juicing, collect 10.0 mL of samples respectively, centrifuge at 10000r / min for 10 min, and store the supernatant at room temperature for later use. For black tea, just change the mass to 0.1 g; The cabbage purchased from the supermarket was hydroponically cultivated with its roots preserved. After 10 days of cultivation, 10 mL of 1 mg / mL cartap standard solution was sprayed on it. The next day, 5 g of the cultivated cabbage was weighed, 40 mL of water was added, and the juice was squeezed, filtered, and centrifuged. The supernatant was aspirated and diluted 10 times for later use. The above steps were repeated after 5, 10, 15, and 20 days respectively until the residual value of cartap was traced to 0; (4) In order to obtain the best enzyme performance material, this example is to CeO2 / ZrO2@ p-β The synthesis conditions of -CD nanozyme were optimized, including the mass concentration of polycyclodextrin, metal feed ratio, amount of ammonia water, reaction temperature and reaction time, and the optimal conditions were determined to be 0.02 wt%, 9:1, 800 μL, 110 o C, 15 min.

[0031] (5) In order to obtain the best nanozyme performance, CeO2 / ZrO2@ p-β Before studying the catalytic activity of -CD oxidase, the reaction time (0-3600 s), pH (2.5-6.0), and TMB dosage (50-300 μL) were optimized. Figure 4 The results show that CeO2 / ZrO2@ p-β The optimal experimental conditions for -CD nanozyme were pH 4.00, 150 μL (1.5 mM) TMB, and aging at 25 °C for 2400 s.

[0032] (6) CeO2 / ZrO2@ p-β -Exploration of the kinetic parameters of CD nanozymes: In this example, under the optimal experimental conditions (150 μL 0.08 mg / mL CeO2 / ZrO2@ p-β -CD, pH 4.0, 150 μL 1.5 mM TMB, aged at room temperature for 2400 s) was used to perform kinetic experiments on simulated oxidase. Figure 5 As shown. The concentration of TMB (0.0375~0.075 mmol / L) was changed, and the absorption intensity of the ultraviolet absorption peak at 652 nm within 600.0 s was recorded. According to the Michaelis-Menten equation, the corresponding initial reaction rate v was calculated, and the relationship between the reaction rate and TMB concentration was plotted (v- c TMB ) and the double reciprocal curve of the inverse of the reaction rate and the inverse of the TMB concentration according to the Lineweaver-Burk equation ((1 / v)-(1 / c TMB )) and then calculate CeO2 / ZrO2@p-β -CD-catalyzed TMB Michaelis constant ( K m ) and the maximum reaction rate ( V max ) are 0.015 mM / 4.98×10 −8 M.s −1 Both are superior to 0.026 mM / 2.16×10 of CeO2 / ZrO2 nanoparticles −8 M.s −1 .

[0033] (7) Catalytic visual detection of selectivity of cartap: Take 50 mL beaker, 6 mL (0.08 mg / mL) p-β -CD@CeO2-ZrO2, 8 mL (pH 4.0) citric acid-sodium hydrogen phosphate buffer solution and 6 mL (1.5 mM) TMB were aged at room temperature for 40 min, and 500 μL of the obtained p-β -CD@CeO2-ZrO2-TMB system, add 60 μL of cartap and other interfering substances, dilute to 3 mL with triple distilled water, mix well and age at room temperature for 5 min, measure its UV-visible spectrum from 300 to 800 nm and observe its color change. The results are as follows Figure 7 As shown in a, all interfering substances (2×10 −5 M of K + , Ca 2+ , Mg 2+ , Cl − , NO3 − , SO4 2− , threonine, lysine, proline and 2×10 −5 g / mL of malathion, cyclosporin A, tolazoline, progesterone, chlorpropamide, chlorfenapyr, chloramphenicol, DDV, BSA and 10 −6 In the presence of MVC, only cartap can p-β -CD@CeO2-ZrO2-TMB system has a UV-visible spectral quenching at 652 nm, and the color ( Figure 7 c) fades from blue to colorless, indicating p-β The -CD@CeO2-ZrO2-TMB system has a special subtractive response to cartap, with good visual detection and spectral response, and no obvious interference from common interfering substances.

[0034] On this basis, a further selective experiment was conducted under the condition of coexistence of cartap and other interfering substances. The intensity change of the ultraviolet absorption peak at 652nm was as follows: Figure 7b. The results show that when cartap coexists with other interfering substances, the intensity of the UV absorption peak does not change substantially, within a 5% error range. This indicates that the coexistence of other interfering substances and cartap has no effect on the detection of cartap. p-β -CD@CeO2-ZrO2-TMB system can be used to simultaneously amplify the signal and visually detect cartap.

[0035] (8) CeO2 / ZrO2@ p-β -CD catalytic visual detection of cartap quantitative parameters: In order to determine the CeO2 / ZrO2@ p-β -CD catalytic visual detection of cartap quantitative parameters (i.e., the linear range of analytical detection, linear relationship equation and detection limit, etc.), laid the foundation for the subsequent practical application of cartap quantitative detection, and tested the UV-visible spectroscopic titration experiment and color change comparison experiment of cartap at different concentrations. Figure 7 As shown in d, with the gradual increase of cartap concentration, CeO2 / ZrO2@ p-β -CD-TMB system gradually decreases in absorption intensity at 652 nm, accompanied by a color change from blue to colorless ( Figure 7 f). The concentration of cartap was 8.00×10 −8 to 2.00×10 −5 g / mL, ∆ A 652 ( A 0- A 652 )and c cartap There is a good linear relationship between them, and the linear equations are ∆ A 652 =2.281×10 −4 c cartap -0.0041, R 2 =0.9987. Figure 7 e. Basis Figure 7 e can be further deduced that the detection limit of cartap for visual detection is 3.76×10 −8 g / mL (S / N=3). In summary, p-β -CD@CeO2-ZrO2 is an excellent catalytic sensor for the quantitative detection of cartap.

[0036] (9) Application of catalytic visual detection of cartap in samples: Based on the rules of quantitative analysis of cartap in (8), detect the concentration of cartap in each sample solution prepared in (3) above: Take a 3 mL volumetric flask and add 500 μL of the solution in (7) above. p-β-CD@CeO2-ZrO2-TMB system, add 60 μL of the actual sample of cartap in (3) above, dilute to 3 mL with triple distilled water, mix well, age at room temperature for 5 min, and measure the UV-visible spectra at 300-800 nm. A 652 , we can calculate ∆ A 652 After the value is obtained, the corresponding linear regression equation ∆ A 652 =2.281×10 −4 c cartap -0.0041, and finally the concentration of cartap in the sample was calculated; the standard spike method was used to determine the standard deviation (RSD) and recovery rate (%) of cartap.

[0037] Table 1 CeO2 / ZrO2@ p-β - Results of visual detection of cartap by CD-TMB-cartap system (n=5) a a c p-β-CD@CeO2-ZrO2 =0.08 mg / mL, pH=4.0 As shown in Table 1, the standard deviation (RSD) of cartap in the actual samples of catalytic visual detection was less than 3.06%, and the recovery rate was between 97.4% and 103.4%. p-β The -CD@CeO2-ZrO2-TMB system was used to experimentally track the degradation of the pesticide residue carbofuran by plants, and the results are shown in Table 2. In the process of tracking the degradation of carbofuran by plants, it was found that the plants could completely degrade the pesticide residue carbofuran in about 20 days, with RSD less than 3.53% and recovery rates between 98.7% and 102.1%.

[0038] Table 2CeO2 / ZrO2@ p-β -CD-TMB-cartap system to track the results of plant degradation of cartap (n=5) a a c p-β-CD@CeO2-ZrO2 =0.08 mg / mL, pH=4.0 Target CeO2 / ZrO2@ p-β-CD nanozyme can be used to catalyze the visual detection of pesticide residue carbofuran in actual samples, with the characteristics of high sensitivity and accurate detection results.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A CeO2 / ZrO2@ p-β -CD nanozyme, characterized in that The nanozyme uses polycyclodextrin as a carrier and loads CeO2 and ZrO2 crystals through chelation. Through electron microscopy observation, the nanozyme presents a three-dimensional porous network structure.

2. The CeO2 / ZrO2@ of claim 1 p-β -The preparation method of CD nanozyme is characterized by: The method comprises the following steps: adding Ce(NO3)3·6H2O, ZrCl4 and ethylene glycol into an aqueous solution of polymerized cyclodextrin to make them dispersed evenly; and adding ammonia water to prepare the nanozyme through microwave-assisted hydrothermal synthesis.

3. The method for preparing the nanozyme according to claim 2, characterized in that: The aqueous solution of polymerized cyclodextrin is prepared as follows: 4.5-5.5 mg of water-soluble polymerized cyclodextrin is added to 4.0-5.0 mL of water, and the water is fully dissolved by stirring or ultrasonication.

4. The method for preparing the nanozyme according to claim 2, characterized in that: The concentration of the ammonia water is 25-28%, and the mixture is stirred for 1.5-2.5 h after adding the ammonia water.

5. The method for preparing the nanozyme according to claim 2, characterized in that: The dosage ratio of Ce(NO3)3·6H2O, ZrCl4, ethylene glycol, aqueous solution of polymerized cyclodextrin and aqueous ammonia is 17-22 mg: 1.0-1.30 mg: 20 mL: 4.0-5.0 mL: 750-850 μL.

6. The method for preparing the nanozyme according to claim 2, characterized in that: The reaction parameters of the microwave-assisted hydrothermal synthesis are as follows: 105-115° C., 12-20 min, 650-750 W. The reaction product after the microwave-assisted hydrothermal synthesis is centrifuged to retain the solid part, and the nanozyme is obtained after washing.

7. Use of the nanozyme according to claim 1 as an oxide mimetic enzyme.

8. A catalytic sensor of cartap, characterized in that: The sensor comprises the nanozyme as described in claim 1 and also comprises a color developing substrate.

9. The catalytic sensor of cartap according to claim 8, characterized in that: The chromogenic substrate is OPD or TMB; when the chromogenic substrate is TMB, the preparation method of the catalytic sensor is as follows: the nanozyme according to claim 1, 1.3~1.6mM TMB and a citric acid-disodium hydrogen phosphate buffer solution with a pH of 3.5~4.5 are mixed and aged at room temperature, with a dosage ratio of 0.45~0.55 mg: 120~170 μL: 6~10 mL. After mixing evenly, the mixture is aged at room temperature for 35~45 min.

10. A catalytic detection method for cartap, characterized in that: The steps include: preparing the catalytic sensor according to claim 8 or 9, adding 50-70 μL of the sample to be tested into the sensor reaction system, mixing evenly at room temperature and aging for 4-6 minutes, detecting the absorbance value by ultraviolet spectroscopy, and calculating the absorbance value by linear equation ∆ A 652 =2.281×10 −4 c cartap -0.0041Calculate the concentration of cartap in the sample to be tested.

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